Currently, some special vehicles such as inspection vehicles need to perform guidance by their own. In general, as shown in FIG. 1, it needs to install a laser, two laser distance-measuring sensors and a set of reference baffles at one side of these vehicles. A vehicle 10′ travels along a direction of an arrow. Before an initial guidance, it is necessary to set a distance between a vehicle body of the vehicle 10′ and the reference baffle GB in advance. When the vehicle 10′ for inspection is moving, in accordance with an output signal from the two sensors, different distances d1 and d2 between the vehicle for inspection and the reference baffle GB respectively can be obtained. Based on the relationship between the distances d1 and d2, a posture of the vehicle body is analyzed. When the distance d1 is not equal to the distance d2, i.e., an inclination degree of the vehicle body with respect to the reference baffle or a distance of the vehicle body transversely offset from an imaginary reference line exceeds a preset range, a correction system enables to adjust the posture of the vehicle body by means of an actuating mechanism, so that the vehicle body travels along a straight line parallel to the reference baffle, that is, the distance d1 is equal to the distance d2, or the distance d1 is close to the distance d2. When the inclination degree of the vehicle body with respect to the reference baffle or the distance of the vehicle body transversely offset from the imaginary reference line exceeds an adjustable range, the system will report an error for stopping the vehicle, to protect a scanning system therein to be safe.
However, in the prior art, it is normally necessary to install a certain length of the reference baffle. Due to different traveling distances for different inspection vehicles, the joined baffles will have a length from tens of meters up to a hundred of meters. After each translation of the location, these reference baffles need to be installed again, and it is not convenient to operate them on the spot. Since the reference baffles are huge bulky, and the transfer and transportation thereof are not convenient, it cannot efficiently satisfy needs of the inspection vehicles to frequently transfer from location to location. Such correcting way makes a relatively high demand on the producing process and installing precision of the reference baffles. That is, the surface of the baffles shall be flat and uniform. After joining the baffles, they shall be kept substantially in parallel to the predetermined travelling trace of the vehicle. Otherwise, it will result in a relatively large correction error.